Die cast zinc base alloy product



Patented Sept. 26, 1933 UNITED STATES DIE CAST ZINC John B. Freeman,

signor to The Waterbury, Conn., icut No Drawing.

- Serial BASE ALLOY PRODUCT Jr., Waterbury, American Brass a corporation of Conn, as-

Company, Connect- Application December 1'1, 1931 4 Claims. (61. 15-1) This invention relates tov die cast zinc base alloy products and has for its object the provision as a new article of manufacture of improved zinc base.

alloy products of this nature. 6 The design of the usual type of die casting machine is such that the mechanism is to a great extent completely immersed in the molten alloy to be cast. The mechanical requirements of the die casting process as carried out in the plunger or goose-neck machines are such that many of the working parts of the machine must be constructed of iron or steel. These metals are subject to attack by molten zinc and zinc alloys and it is known from experience that to minimize this attack sufficiently in order to obtain reasonable life from the machines it is necessary-that at least 0.25% of aluminum be present in the alloys. It is known further that al um when present in zinc base alloys even in amounts less than 0.25%

0 causes a disintegration or intercrystalline corrosion to occur more especially in warm and humid atmospheres, but amounts less than 0.05 percent of aluminum may not be objectionable although it or at least contain not more than when present in conditions,

more particularly when the stantially free from aluminum, cause a similar disintegration or intercrystalline corrosion to occur. Zinc base alloys containing aluminum are also subject to change in strength, more particularly in impact strength, wi h time even in the absence of moisture.

1 Improved zinc base alloys containing aluminum have been'developed in which the degree of disintegration or intercrystalline oxidation has been reduced by the addition of elements other than aluminum such as copper and more particularly magnesium. A committee ondie cast metals and alloys of The American Society for Testing Materials has series of tests to determine the most suitable alloy or alloys for adoption as standard alloys for the industry. All of the alloys tested contained aluminum and of all the alloys tested only one alloy was found to be sufiiciently stable, that is, free from disintegration or change in physical properties with time. This zinc base alloy has the nominal composition'of 4% aluminum, 3% copper and 0.05% magnesium, and the further requirement that the lead content shall be not greater than- 0.01% and the cadmium and tin contents not greater than 0.005% respectively. .5 It is specified also that the zinc used forthe is preferred that the alloy be free recently conducted an extensivepreparation of the alloy shall contain not more than 0.02% total impurities. The investigations of the above committee have shown that the use of very pure zinc is essential because of the deleterious effect of the impurities normally present 0 in zinc, more particularly lead. It is known also that magnesium is essential in zinc alloys containing aluminum, even when very pure zinc is used to inhibit disintegration in humid atmospheres.

- I have found that die cast zinc base alloy prod-' ucts made of an alloy of zinc and nickel and substantially free from aluminum and magnesium, more particularly an alloy containing from about 0.10 to about 10% of nickeland preferably free from aluminum and magnesium, or containing less than 0.05% of aluminum and less than 0.05 percent magnesium may be prepared successfully and economically in a die castingmachine in which the'melting chamber is entirely separated from the casting mechanism. have found that die cast zinc base alloy products above noted proportions of nickel aluminum and magnesium are stable, not so change in physical properties with time even when subjected to hot humid atmospheres for long period of time. The above range of nickel produces useful alloys, but the preferred range is from about 0.50%. to about 1.5% of nickel. For example there are given in the following tables. the results of tests of a die cast zinc base alloy product prepared from a zinc nickel alloy substantially free from aluminum and magnesium. and of a similar die cast product of an alloy of zinc, copper, aluminum and magnesium. In thetable the properties given for product designated (A) are typical for the new die cast products free or substantially free from aluminum and magnesium for which Letters Patent are desired. The properties for product (B) are typical for die cast product containing aluminum at present widely used in the industry.

Composition of products Zine metal \Prodcontaiu- Nickel, Copper, Aluminum, Magnesium,

not ing impercent percent percent percent purities less than I A---" 0.02 1.02 .Lesstl1an0.0l Lees' than0.01 B.-- 0.02 2.96 4.24 v 0.0!

Product hength,

percent in 2 lbsJsq. in.

inches F I Plwaxcal propertzes after exposure to water vapor for days at a temp rature of C.

. Elongation', perof length of -res1st- 6 inches,

inches Product cal properties remaining practically concm of ten days C. whereas the uired and where 1t would be subject to hot humid atmospheres.-

. eagues 0 Impact Expansion I In the preparation of the new zinc base alloy pmduct I prefer to use zinc of highest purity as is required for alloys but this nickel and the balance zinc.

3. As a new article of manufacture a. die cast product mad nickel and the containing not more than 0.02 percent total impurities.

' JOHN R. REEMAN, JR. 

